This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The primate TRIM5alpha protein mediates a potent, post-entry block to retroviral infection. We are studying the population-genetics of primate TRIM5alpha and using this knowledge to develop better models for HIV-1 replication and pathogenesis, and in ascertaining the effects of TRIM5alpha polymorphism on differential outcome during SIV infection.